A biosystematic study of the Kangaroo Paws, Anigozanthos and Macropidia (Haemodoraceae).

Abstract

Seed set, seed germlnatlon and hybrld pollen fertilltles following controlled pollinations of 4828 flowers were investigated in the 12 species of kangaroo paws to assess taxonomlc and evolutionary relationships, document breeding systems and explore the potential and limitations in syntheesizing horticulturally desirable hybrlds in the group. All species except Anigozanthos flavidus set few seeds on selfing relative to numbers set on intrapopulational crossing, and thus were predominantly outbreeding. Interpopulational crossing barriers in A humilis were usually non-existent. In A. viridis they occurred between races in a geographical pattern consistent wtth the occurrence of the Wallace Effect (reproductive character displacement) In A. bicolor they were complex and generally uncorrelated wlth interpopulational distances or morphological (racial) divergence, while in A. manglesii they were associated consistently wlth racial differences. Interspecific crosses involving 79 species combinations and 215 population combinations invariably revealed crossing barriers more potent than those seen in intraspecific crosses. The biosystematic data support the taxonomic conclusions that Anigozanthos and Macropidra are genetically isolated genera, that recognition of just two sections (Anigozanthos and Hapianthesis) represents the best subgeneric classification of Anlgozanthos and that members of the A. bicolor-A. gabrielae, A viridis, A humilis-A kalbarriensis and A rufus-A pulcherrimus groups each constitute distinct species rather than intraspecific taxa The majority of Interspecific F₁ hybrids were found to succumb to fungal attack, snail predation and/or inappropriate watering within 2 or 3 years of cultivation Hybrids of A. flavidus appeared to be the most vigorous, long-lived and floriferous, and probably are the most suitable for large-scale horticultural development